Zhang Kai, Daixingjian, Dong Jinping
Tsinghua University, China
Keywords: Flywheel, Energy Storage, Hybrid bearings, Active magnetic bearingEnergy storage flywheels are important for energy recycling applications such as cranes, subway trains. In a petroleum field, an oil rig runs with big load variation. A vertical flywheel system had been tested to stabilize the load fluctuation and proved its effectiveness. To improve bearing life, a new flywheel was designed. The key was usage of hybrid bearings including an axial permanent magnetic bearing (PMB), a lower end ball bearing and an upper end active magnetic bearing (AMB). The design combined advantages of the different bearings to improve system reliability. The ball bearing was cheap and reliable but needed lubrication and its static load was limited at high rotation speeds. For upper end support, a lubrication system for a ball bearing was complex and difficult to maintain. The AMB was no lubrication, dynamic controllable and suitable for high speed rotors with small dynamic load. Though cost more, it was used in upper end. The PMB was cheap and energy-saving. It removed most static load for the vertical rotor and benefit the ball bearing life and the system power lost. The new system structure was shown and the important parameters including the hybrid bearing feathers were provided.